<template>
  <canvas
    class="ec-canvas"
    :canvas-id="canvasId"
    @init="init"
    @touchstart="touchStart"
    @touchmove="touchMove"
    @touchend="touchEnd"
    :style="customStyle"
  >
  </canvas>
</template>

<script>
import WxCanvas from './wx-canvas'
import * as echarts from './echarts'

function wrapTouch(event) {
  for (let i = 0; i < event.touches.length; ++i) {
    const touch = event.touches[i]
    touch.offsetX = touch.x
    touch.offsetY = touch.y
  }
  return event
}

let ctx;

export default {
  props: {
    canvasId: {
      type: String,
      value: 'ec-canvas'
    },
    ec: {
      type: Object
    },
    customStyle: {
      type: String,
      default: 'width: 100%;height: 100%;'
    }
  },
  data() {
    return {
      // 只能用 $ 开头的变量名，否则报 JSON 循环错误？
      $chart: {}
    };
  },
  methods: {
    init(callback) {
      const version = wx.version.version.split('.').map(n => parseInt(n, 10));
      const isValid = version[0] > 1 || (version[0] === 1 && version[1] > 9) ||
        (version[0] === 1 && version[1] === 9 && version[2] >= 91);
      if (!isValid) {
        console.error('微信基础库版本过低，需大于等于 1.9.91。' +
          '参见：https://github.com/ecomfe/echarts-for-weixin' +
          '#%E5%BE%AE%E4%BF%A1%E7%89%88%E6%9C%AC%E8%A6%81%E6%B1%82');
        return;
      }

      ctx = wx.createCanvasContext(this.canvasId, this);

      const canvas = new WxCanvas(ctx, this.canvasId);

      echarts.setCanvasCreator(() => {
        return canvas;
      });

      var query = wx.createSelectorQuery().in(this);
      query.select('.ec-canvas').boundingClientRect(res => {
        // fixed by xy
        this.$chart = this._initChart(canvas, res.width, res.height);
      }).exec();
    },
    // created by xy 修改图表的数据
    updateOption(value) {
      this.$chart.setOption(value);
    },
    // created by xy 将初始化 charts 放在组件内
    _initChart(canvas, width, height) {
      const chart = echarts.init(canvas, null, {
        width,
        height
      });
      canvas.setChart(chart);
      chart.setOption(this.ec.option);
      return chart;
    },
    canvasToTempFilePath(opt) {
      if (!opt.canvasId) {
        opt.canvasId = this.canvasId;
      }

      ctx.draw(true, () => {
        wx.canvasToTempFilePath(opt, this);
      });
    },
    touchStart(e) {
      if (this.ec.stopTouchEvent) {
        e.preventDefault()
        e.stopPropagation()
        return
      }
      if (this.$chart && e.touches.length > 0) {
        var touch = e.touches[0];
        var handler = this.$chart.getZr().handler;
        handler.dispatch('mousedown', {
          zrX: touch.x,
          zrY: touch.y
        });
        handler.dispatch('mousemove', {
          zrX: touch.x,
          zrY: touch.y
        });
        handler.processGesture(wrapTouch(e), 'start');
      }
    },
    touchMove(e) {
      if (this.ec.stopTouchEvent) {
        e.preventDefault()
        e.stopPropagation()
        return
      }
      if (this.$chart && e.touches.length > 0) {
        var touch = e.touches[0];
        var handler = this.$chart.getZr().handler;
        handler.dispatch('mousemove', {
          zrX: touch.x,
          zrY: touch.y
        });
        handler.processGesture(wrapTouch(e), 'change');
      }
    },
    touchEnd(e) {
      if (this.ec.stopTouchEvent) {
        e.preventDefault()
        e.stopPropagation()
        return
      }
      if (this.$chart) {
        const touch = e.changedTouches ? e.changedTouches[0] : {};
        var handler = this.$chart.getZr().handler;
        handler.dispatch('mouseup', {
          zrX: touch.x,
          zrY: touch.y
        });
        handler.dispatch('click', {
          zrX: touch.x,
          zrY: touch.y
        });
        handler.processGesture(wrapTouch(e), 'end');
      }
    }
  },
  created() {
    if (!this.ec) {
      console.warn('组件需绑定 ec 变量，例：<ec-canvas id="mychart-dom-bar" ' +
        'canvas-id="mychart-bar" ec="{{ ec }}"></ec-canvas>');
      return;
    }

    if (!this.ec.lazyLoad) {
      this.init();
    }
  }
}
</script>

<style>
.ec-canvas {
  width: 100%;
  height: 100%;
}
</style>
